Thought I would pass this on to others whom might be interested in hearing more about the GM Clutch Hydraulic System Actuator (slave cylinder) quality spill issue. Before getting into further details of the quality assurance issue, I would like to explain a few basic details about the different types of clutch hydraulic actuators which are available on the market.


GM and NAPA sell the TRW manufactured actuator which is made of a Draw Over Mandrel (DOM) tube construction and has a black powder coat finish. Other companies such as Checker and AutoZone sell the WAGNER manufactured actuator which has a cast body construction. Same goes for the master cylinders as well.


Several weeks ago my partner Gregg Creevy and I were dissecting three new DOM style actuators when we found that all of the seals were installed backwards. Based on the previous DOM style actuators installed into customer vehicles which by the way failed within a few hours to a few weeks of operation and how they acted prior to failing, it is our speculation that these DOM type actuators have been having the seals installed backwards for the last two to two and a half years.


Getting this information to GM Quality Control Group was the one aspect that we did not know how to do. I called Hib Halverson to ask what he would do. Hib suggested that I call Stan Lorence from Tom Henry Chevrolet Parts and advise him of our findings. As it turned out, Hib was right on the money. Stan went straight to the highest point of contact within GM SPO Quality assurance group.


Many thanks to Hib Halverson and Stan Lorence for your efforts in getting this information to the people who can make this problem go away. Also many thanks to Jeff DeBuhr on the Corvette Forum for corresponding with others to make them aware of this quality assurance issue as well as providing GM with a visible queue of public awareness regarding the existence of this problem. The following messages are correspondence sent from Stan to GM SPO and received from GM SPO back to Stan. Thanks again everybody for your help, Stan especially.


Sent: Friday, May 26, 2006 4:50 PM Subject: Corvette slave cylinders

Hi John, The following was sent to me by one of my customers, Bill Boudreau a nationally know Corvette expert, and appears on the Corvette Forum website. It concerns the Corvette C4 clutch slave cylinder which, in my experience, has a very high failure rate. Nearly half of them sold over the counter are returned to me as defective.


Please visit the following web address for an explanation of the failures. These failures have been an issue for over two years. This seemed to me to be an important enough issue that I needed to let someone at GM know. I spoke with my parts rep Casey Rentfrow, who is always very helpful, and he suggested that I email you the information.


My customer, Bill Boudreau, has been attempting to procure the affected seals (part number AAD-34665237) without success. He states that they must be highly proprietary because he has access to all the major manufacturers and they cannot or will not supply them to him. He has asked me to approach GM on his behalf and request that these seals be made available. After you review and consider this information I ask that you keep me informed and "in the loop".


Thank you in advance for your attention.



Stan Lorence

Tom Henry Chevrolet Parts.






-- Bill Boudreau

Actions: E-mail | Permalink |

The information contained in this website is for general information purposes only. Whilst we endeavor to keep the information up-to-date and correct, we make no representations or warranties of any kind, express or implied, about the completeness, accuracy, reliability, suitability or availability with respect to the website or the information, products, services, or related graphics contained on the website for any purpose. Any reliance you place on such information is therefore strictly at your own risk.

In no event will we be liable for any loss or damage including without limitation, indirect or consequential loss or damage, or any loss or damage whatsoever arising from loss of data or profits arising out of or in connection with the use of this website.

Through this website there are links to other websites which are not under the control of the ZR-1 Net Registry. We have no control over the nature, content and availability of those sites. The inclusion of any links does not necessarily imply a recommendation or endorse the views expressed within them.

Read the full Disclaimer...

©2019 ZR-1 NET Registry   |  Privacy Statement